Desired armor protection levels can usually be obtained if weight is not a consideration. However, in many armor applications, there is a premium put on lightweight armor. Some areas of application where lightweight armor are important include ground combat and tactical vehicles, portable hardened shelters, helicopters, and various other aircraft used by the Army and the other Services. Another example of an armor application in need of reduced weight is personnel body armor worn by soldiers and law enforcement personnel.
There are two prevalent hard passive armor technologies in general use. The first and most traditional approach makes use of metals such as armor grade steel. The second approach uses ceramics. Each material has certain advantages and limitations. Broadly speaking, metals are more ductile and are generally superior at withstanding multiple hits. However, they typically have a large weight penalty and are not as efficient at stopping armor-piercing threats. Ceramics are extraordinarily hard, strong in compression, lighter weight, and brittle, making them efficient at eroding and shattering armor-piercing threats, but not as effective at withstanding multiple hits.
Attempts to take advantage of the best characteristics of the metal and the ceramic have been tried. For example, ceramic tiles have been encapsulated in a metal framework using a hot-press process followed by extensive grinding and finishing to produce an acceptable armor article. The grinding and finishing (post-processing) steps are expensive and time consuming processes. Moreover, additional processing is required to build the metal matrix or frame that connects multiple ceramic tiles. The metal frame is typically a piece of solid steel precision machined to create openings that mirror the tile dimensions or is slightly undersized then heated and the tiles are shrink fit into the matrix. Metal plates are then added to both the front and back of the metal frame and super-plastically bonded to the metal frame thus totally encapsulating the tiles. This process is lengthy and costly.
One such method of encasing ceramic tiles in a metal frame is disclosed in U.S. Pat. No. 5,686,689 to Snedeker, et al. Ceramic tiles were placed into individual cells of a metallic frame consisting of a backing plate and thin surrounding walls. A metallic cover was then welded over each cell, encasing the ceramic tiles. A benefit to encasing the ceramic tile is that once fractured pieces cannot move away easily and a degree of protection is maintained in the area of the ceramic tile.
Substantial development efforts are ongoing with metal encapsulated ceramic tiles or plates to find more cost-effective and faster production methods that utilize the advantages of both materials to maintain or lower the armor's weight and to decrease the negative effects of fractured tiles such as reduced penetration resistance and damage to neighboring tiles, while also improving the ceramic's integrity during the metal encapsulation process.